Ionization chamber



c. .1. BORKOWSKI 2,479,600

ICNIZATION CHAMBER Filed June 19, 1945 Patented Aug. 23, 1949 IONIZATION CHAMBER Casimer J. Borkowski, Oak Ridge, Tenn., assignor to the United States of America as represented by the United States Atomic Energy Commission Application June 19, 1945, Serial No. 600,401

3 Claims. (Cl. 250-275) This invention relates to ionization chambers, and more particularly to such chambers adapted to measure the radioactivity of a gas. Chambers of the type to which this invention relates are commonly called Geiger-Muller counters.

An object of the invention is to provide a counter tube simple in design and easily assembled in proper relationship.

Other objects of the invention are attained by the particular arrangement and organization of parts, all of which will be evident from the following description when read in connection with the accompanying drawing in which Fig. 1 is a view in perspective of a preferred embodiment of the invention with a portion broken away and a part shown in outline, and Fig. 2 shows in perspective the part shown in outline in Fig. 1 and with a portion broken away.

As shown in the drawing, the preferred embodiment of the invention comprises a cylindrical glass envelope l having a constricted end H leading through a stop-cock l2 to a tapered fitting l3 for easy connection to suitable evacuating and gassin apparatus (not shown). Th other end of the envelope I0 is provided with a neck portion [4 having an internal bore l5 tapered to receive snugly a plug member [6 formed with a corresponding taper on a portion of its exterior. The tapered glass surfaces and I6 are preferably ground for reasons well understood. A small diameter rod or wire I! is sealed in the plug IE to extend coaxially therewith. For a purpose explained below, the plug 16 has a cylindrical sleeve portion I8 of reduced diameter extending over the wire I1.

3 Inc inner surface of the envelope I0 is provid.d with a coating IQ of conductin material, preferably aquadag, which is made electrically available to the exterior of the envelope ID by a sealed-in lead 20 for the application of a high voltage. The interior and exterior of the neck portion I4 are also given a conducting coating, as shown, to which an external lead 2| is connected. In normal use. the lead 2| will be connected to ground as is well known practice.

The tapered portion of the plug 46 and the exterior of the sleev "3 are provided with a continuous layer of conducting material, preferably aquadag, so that when the plu [6 is positioned in the neck [4 as indicated in Fig. 1 such layer is electrically connected to the ground lead 2 I. The coating on the sleeve 18 thus constitutes an accurately positioned guard ring.

It will be appreciated that the neck H is so oriented with respect to the envelope 10 that the electrode l1 and the guard ring on the sleeve H! are properly positioned with respect to the electrode [9 when the plug I6 is pressed home in the neck l4. To insure a gas tight fit between the plug l6 and the neck 14 a fillet 22 of suitable wax may be applied at the juncture of the plug is and the bead of the neck M.

The tube above described when suitably connected to a voltage supply and sensitive circuit in any well known manner will function as a counter tube with the wire 11 comprising the collecting electrode. A gas to be counted ma by suitable obvious arrangements be admitted into the envelope in through the stop-cock I2 and, after counting is completed. be evacuated therefrom.

The tube provided by this invention is simple in structure, is easy to assembly properly, and functions satisfactorily. Modifications and variations in its structure will be evident to those skilled in the art, and such modifications and variations are intended to be included in the appended claims.

I claim:

1. An ionization chamber for measuring the radioactivity of a gas within the chamber comprising a cylindrical glass envelope having a neck portion with a. tapered bore, a glass plug member having an external surface correspondingly tapered and adapted to fit snugly in said bore, a conducting rod axially centered and sealed in said plug member so that it constitutes a central collecting electrode when said plug is seated in said bore, said plug havin a tubular extension projecting from the smaller end of its tapered portion and surrounding said rod for a portion of its length, a layer of conducting material on the internal surface of said envelope opposed to the exposed portion of said rod, a lead-in wire to said layer, a conducting material coated on the external surface of said plug and its tubular extension, and means on said neck portion cooperating with said conducting material to provide a conducting path from said tubular extension to the exterior of said envelope whereby a guard ring is provided for the collecting electrode rod.

2. A chamber as claimed in claim 1 in which the conducting material is graphite.

3. An ionization chamber including a glass envelope, a conducting lining within said envelope providing an outer electrode, a central collecting electrode fused in a tapered glass sleeve adapted to fit a corresponding portion of said chamber, a coating of conducting material on the exterior of said sleeve to serve as a guard ring, an unlined portion of said envelope providing electrical insulation between said outer electrode and said guard ring, and an uncoated p rtion of said sleeve providing electrical insulation between said central collecting electrode and said guard ring.

CASIMER J. BORKOWSKI.

'4 REFERENCES crrnn The following references are of record in the file of this patent: 

